Grease compositions



United States Patent 3,429,814 GREASE COMPOSITIONS Herbert Myers, Barrington, William F. Olszewski, Cherry Hill, and Richard A. Butcosk, Westmont, N.J., assignors to Mobil Oil Corporation, a corporation of New York No Drawing. Filed Apr. 5, 1966, Ser. No. 540,220 U.S. Cl. 25248.2 4 Claims Int. Cl. Cltlm 7/40 ABSTRACT OF THE DISCLOSURE This invention relates to the use of resorcinol sulfides as load-carrying and anti-wear agents in lubricating greases.

This invention relates to lubricating grease compositions and, in accordance with its objects, relates more particularly to lubricating grease compositions having improved load-carrying and anti-Wear properties. Still more particularly, the invention relates to lubricating grease compositions containing, as load-carrying improvers and anti-wear agents, resorcinol sulfides, and to a new and improved method for preparing the latter.

In general, as more fully hereinafter described, the novel grease compositions of the present invention comprise a lubricating vehicle, a grease-forming quantity of a thickening agent, and a small amount, sufficient to improve the load-carrying and anti-Wear properties of the grease composition, an additive, comprising a resorcinol sulfide, which is employed either in the form of resorcinol monosulfide or resorcinol disulfide.

In its more specific aspects, the aforementioned resorcinol sulfide additives are generally incorporated in the grease in an amount of at least about 0.1 percent, by weight, and, preferably, from about 0.1 to about 20 percent, by weight, of the total grease composition. The most effective load-carrying and anti-wear properties, moreover, have been obtained when the resorcinol sulfide additive is present in an amount from about 0.5 to about percent, by weight, of the total grease composition.

The aforementioned resorcinol sulfide additive may be effectively incorporated in grease compositions, generally, and such greases may comprise a combination of a wide variety of lubricating vehicles and thickening or gelling agents. Thus, greases in which the aforementioned resorcinol sulfides are particularly elfective, may comprise any of the conventional hydrocarbon oils of lubricating viscosity, as the oil vehicle, and may include mineral or synthetic lubricating oils, aliphatic phosphates, esters and di-esters, silicates, siloxanes and oxalkyl ethers and esters. Mineral lubricating oils, employed as the lubricating vehicle, may be of any suitable lubricating viscosity range from about 45 SSU at 100 F. to about 6,000 SSU at 100 F., and, preferably, from about 50 to about 250 SSU at 210 F. These oils may have viscosity indexes varying from below 0 to about 100 or higher. Viscosity indexes from about 70 to about 95 are preferred. The average molecular Weights of these oils may range from about 250 to about 800. The lubricating oil is employed in the grease composition in an amount suflicient to constitute the balance of the total grease composition, after accounting for the desired quantity of the thickening agent and the resorcinol sulfide additive which is to be incorporated in the grease formulation.

As previously indicated, the oil vehicles employed in the novel grease formulations of the present invention,

3,429,814 Patented Feb. 25, 1969 in which the aforementioned resorcinal sulfides are incorporated as load-carrying improvers and anti-wear agents, may comprise miner-a1 or synthetic oils of lubricating viscosity. When high temperature stability is not a requirement of the finished grease, mineral oils having a viscosity of at least 40 SSU at F., and particularly )those falling within the range from about 60 SSU to about 6,000 SSU at 100 F., may be employed. In instances, where synthetic vehicles are employed rather than mineral oils, or in combination therewith, as the lubricating vehicle, various compounds of this type may be successfully utilized. Typical synthetic vehicles include: polypropylene, polypropylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, di-.(2- ethyl hexyl) sebacate, di-(Z-ethyl hexyl) adipate, di-butyl phthalate, fluorocarbons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chaintype polyphenyls, siloxanes and silicones (poly-siloxanes), alkyl-substituted diphenyl ethers typified by a butyl-substituted bis (p-phenoxy phenyl) ether, phenoxy phenyl ethers, etc.

The lubricating vehicles of the aforementioned improved greases of the present invention containing the above-described resorcinol sulfides as additives, are combined with a grease-forming quantity of a thickening agent. For this purpose, a wide variety of materials may be employed. These thickening or gelling agents may include any of the conventional metal salts or soaps, which are dispersed in the lubricating vehicle in grease-forming quantities, in such degree as to impart to the resulting grease composition, the desired consistency. Other thickening agents that may be employed in the grease formulation may comprise the non-soap thickeners, such as surface-modified clays and silicas, aryl ureas, calcium complexes and similar materials. In general, grease thickeners may be employed which do not melt and dissolve when used at the required temperature within a particular environment; however, in all other respects, any material which is normally employed for thickening or gelling hydrocarbon fluids for forming greases, can be used in preparing the aforementioned improved greases in accordance with the present invention.

As previously described, the load-carrying improvers and anti-wear agents of the novel greases of the present invention comprise resorcinol sulfides either in the form of the monosulfide or the disulfide. In accordance with the novel method for producing these resorcinol sulfides, a solution of resorcinol in a polar solvent is reacted with a solution of a sulfur chloride of the group consisting of sulfur monochloride and sulfur dichloride, in a nonpolar solvent. The reaction between the resorcinol and sulfur chloride can be carried out at room temperature, although temperatures from about 0 C. to about 30 C., or higher, may also be successfully employed. Insofar as the resorcinol and sulfur chloride reactants are concerned, these components are generally employed in a mole ratio of at least about 1:1, and, preferably, in a mole ratio from about 1:1 to about 2: 1. Thus, it has been found that resorcinol monosulfide or resorcinol disulfide can be produced in high yield, at room temperature, by the reaction of 4 moles of resorcinol in solution with 1,4-dioxane, as the polar solvent, with 3 moles of sulfur dichloride or sulfur monochloride, respectively, in solution with benzene as the non-polar solvent. Other examples of the polar solvent that can be employed for solution with the resorcinol sulfide reactant include alkyl ethers and alkyl esters of low molecular weight fatty acids. Other examples, of the non-polar solvent that can be employed for solution with the sulfur monochloride orthe sulfur dichloride include carbon disulfide, aromatic hydrocarbons, higher molecular weight aliphatic hydrocarbons and carbon tetrachloride.

In carrying out the aforementioned reaction it is necessary to add the solution of the resorcinol in the polar solvent to the solution of the sulfur chloride in the nonpolar solvent. This technique permits the precipitation of the resorcinol sulfide and facilitates isolation by filtration. The resulting product is a solid, and is therefore easily handled. In general, it is desirable to employ an excess of the non-polar solvent with respect to the polar solvent. Thus, in this respect, such ratios may be employed, of non-polar solvent to polar solvent, from about :1 to about :1, by volume, and, preferably, ratios of about 10:1 or higher, in order to obtain a more rapid precipitation of the resorcinol sulfide. Insofar as the reaction temperature is concerned, as was previously indicated, the reaction may be carried out at room temperature, or at temperatures varying from about 0 C. to about 30 (3., or higher. Preferably, however, a temperarange from about C. to about 30 C. produces the optimum results, inasmuch as the use of higher temperatures may lead to a softening of the reaction product with the formation of semi-solid materials.

The following examples will serve to illustrate the novel and improved method of reacting resorcinol with sulfur chlorides to produce the corresponding resorcinolsulfide additive, to be employed in the desired grease formulation.

EXAMPLE 1 This example illustrates the reaction of resorcinol with sulfur dichloride to produce resorcinol monosulfide.

155 grams (1.5 moles) of sulfur dichloride and 2500 ml. of benzene were charged to a flask equipped with a stirrer, condenser, thermometer and dropping funnel. 220 grams (2.0 moles) of resorcinol were dissolved in 250 ml. of 1,4-dioxane, with slight warming to approximately 50 C., and were then charged to the dropping funnel. The resorcinol solution was added dropwise over a period of 4 hours to the sulfur dichloride solution at room temperature. The reaction was very mildly exothermic, with the temperature rising to a maximum of 30 C. The addition of the resorcinol solution was accompanied by the evolution of hydrogen chloride and the precipitation of a black solid. After the addition of the resorcinol solution was complete, the reaction mixture was blown with a stream of nitrogen for a period for one-half hour to aid in the removal of hydrogen chloride. The reaction mixture was then filtered, and the residue was allowed to dry and produced a yield of 212 grams of resorcinol monosulfide.

2 3Product analysis-Wt. percent: Sulfur, 20.6; chlorine, EXAMPLE 2 This example illustrates the reaction of resorcinol with sulfur monochloride to produce resorcinol disulfide,

Following the procedure described in Example 1, 101 grams (0.75 mole) of sulfur monochloride were dissolved in 1250 ml. of benzene, and the resulting solution was reacted with 110 grams (1.0 mole) of resorcinol dissolved in 125 ml. of 1,4-dioxane. After reaction and subsequent treatment, in the manner described in Example 1, was carried out, it was found that 139 grams of resorcinol disulfide has been produced.

Product analysis.Wt. percent: Sulfur, 28.1; chlorine, 1.44.

In order to determine the effectiveness of the aforementioned resorcinol sulfides in grease compositions, they were evaluated as extreme pressure and anti-wear agents, employing the standard conventional Shell 4-Ball machine in accordance with Federal Method 6503.1 (July 27, 1964). This Shell 4-Ball machine is conventionally employed to investigate the relative ability of lubricants to lubricate a sliding metallic contact, and determines the load-carrying ability of a lubricant under extremely high pressure. In this test a rotating steel ball is pressed against a triangle of specimen-lubricated stationary steel balls (in a series of tests over a range of pressures until welding occurs). The scars on the balls are measured and the Mean Hertz Load is calculated from the diameters of the scars produced.

Employing the above-described test method, the following base greases, both untreated as well as having incorporated therein the resorcinol sulfides of Examples 1 and 2, were evaluated:

Lithium/ calcium base (Example 3) Mineral oil SUS F 90.0

As is shown in the following table, resorcinol monosulfide, prepared in accordance with Example 1, and resorcinol disulfide, prepared in accordance with Example 2 were individually incorporated in each of the abovedescribed base greases, in the concentrations indicated, for the purpose of determining the aforementioned critical Mean Hertz Load value.

TABLE Oonc., Mean Example Base grease Additive wt. Hertz percent load (3) Lithium/calcium base.-. None None 26.3 (4) do Ex. 1 1. 0 32. 1 (5)-. 1. 0 39. 6 (6) None 21. 8 1. 0 29. 6 8) dn 1. 0 29. 4 (9) Soda base None None 22. 3 (10) do Ex. 1 1. O 25. 8 (11) do Ex. 2 1.0 29.0 (12) Silica base None None 20. 4 (13) do Ex. 1 1.0 31.3 (14) do Ex. 2 1. 0 34. 9

From the data of the foregoing examples, it will be apparent that the resorcinol sulfides of the present invention may be effectively incorporated in a wide variety of grease compositions, for the purpose of improving their load-carrying and anti-wear properties. It will also be understood that such grease compositions can also contain other characterizing materials, lubricating vehicles and fillers, and may include, for example, various antioxidants, lubricity improving agents and the like. These characterizing materials do not detract from the lubricating value, but, rather, serve to impart their customary properties to the grease. Although the present invention has been described with preferred embodiments, various modifications and adaptations thereof may be resorted to without departing from the spirit of the invention, as those skilled in the art will readily understand.

We claim:

1. A grease composition comprising a lubricating vehicle, a grease-forming quantity of a thickening agent and a small amount, suflicient to improve the load-carrying and anti-wear properties of said grease, of a resorcinol sulfide selected from the group consisting of resorcinol monosulfide and resorcinol disulfide 2. A composition in accordance with claim 1, wherein said resorcinol sulfide is present in an amount of at least about 0.1 percent, by weight, of the total of said composition.

3. A composition in accordance with claim 1, wherein said resorcinol sulfide is present in an amount from about 0.1 to about 20 percent, by weight, of the total of said composition.

4. A composition in accordance with claim 1, wherein said resorcinol sulfide is present in an amount from about 0.5 to about 5 percent, by weight, of the total of said composition.

References Cited UNITED STATES PATENTS DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN, Assistant Examiner.

US. Cl. X.R. 

